Combustor of a gas turbine engine

ABSTRACT

A combustor has a combustion zone and a liner bounding the combustion zone. The liner has a first end portion and a second end portion spaced a defined distance from the first end portion. The combustor has a convector spaced apart from the liner. The convector has a first end portion and a second end portion spaced a defined distance of the first end portion. A plurality of passages are located between the liner and the convector. One of the passages has a length that is longer than at least one of the defined distance of the liner and the defined distance of the convector.

TECHNICAL FIELD

This invention relates generally to a gas turbine engine and morespecifically to cooling of a liner of a combustor of a gas turbineengine.

BACKGROUND

Current gas turbine engines continue to improve emissions and engineefficiencies. Notwithstanding these improvements, further increases inengine efficiencies will require more effective use of a mass ofcompressed air exiting a compressor. Gas turbine engines normally usethe mass of compressed air for: 1) combustion air, 2) dilution air, 3)combustor cooling air, and 4) turbine component cooling air. Each use ofthe mass of compressed air may vary according to a load on the gasturbine engine. Generally each of these uses requires more of the massof compressed air as the load increases.

In particular, combustion air and combustor cooling air have increasedin importance with increasing regulations of NOx (an uncertain mixtureof oxides of nitrogen). The efficiencies of the gas turbine engineusually improve with increased temperatures entering a turbine. Unlikethe efficiency of the gas turbine engine, decreasing NOx production ingas turbine engines typically involves reducing a flame temperature.Lean premixed combustion attempts to decrease NOx production whilemaintaining gas turbine engine efficiencies. A lean premixed combustorpremixes a mass of combustion air and a quantity of fuel upstream of aprimary combustion zone. Increasing the mass of combustion air reducesthe flame temperature by slowing a chemical reaction between the fueland the combustion air. By reducing the flame temperature, NOxproduction also decreases. A lean premixed fuel injector assembly isshown in U.S. Pat. No. 5,467,926 issued to Idleman et al. on 21 Nov.1995.

Even with the lower flame temperatures, a liner wall of the combustormust be maintained at an operating temperature meeting a durabilityrequirement. A number of cooling schemes may be used to cool thecombustor liner including film cooling, convection cooling, effusioncooling, and impingement cooling. However, one problem shared by manydifferent cooling schemes is an inability to obtain the maximum coolingpotential from the available mass of cooling air while still maintaininglow emissions. For example, one potential problem with film cooling, avery effective cooling method, is the formation of carbon monoxide atthe periphery of the combustor.

The combustor of the present invention solves one or more of theproblems set forth above.

SUMMARY OF THE INVENTION

An embodiment of a combustor has a combustion zone and a first linerbounding the combustion zone. The first liner has a first end portionand a second end portion spaced a defined distance from the first endportion. The combustor has a first convector spaced apart from the firstliner. The convector has a first end portion and a second end portionspaced a defined distance from the first end portion. The combustor hasa plurality of passages positioned between the first liner and the firstcombustor liner. At least one of the plurality of passages has a lengththat is greater than at least one of the defined distance of the firstliner and the defined distance of the first convector.

An embodiment of a gas turbine engine has a compressor, a combustor, anda turbine. The combustor has a combustion zone and a first linerbounding the combustion zone. The first liner has a first end portionand a second end portion spaced a defined distance from the first endportion. The combustor has a first convector spaced apart from the firstliner. The convector has a first end portion and a second end portionspaced a defined distance from the first end portion. The combustor hasa plurality of passages positioned between the first liner and the firstcombustor liner. At least one of the plurality of passages has a lengththat is greater than at least one of the defined distance of the firstliner and the defined distance of the first convector.

In a further embodiment of the present invention, a method of cooling aliner of a combustor of a gas turbine engine includes directing a fluidbetween a first end portion of a first liner and a first end portion ofa first convector of a combustor. At least one of the first liner andthe first convector has a central axis. The method further includescausing the fluid to move in a direction nonparallel to the centralaxis.

In another embodiment of the present invention, a combustor has acombustion zone and a first liner bounding the combustion zone. Thecombustor has a first convector spaced apart from the first liner. Atleast one of the first liner and the first convector has a central axis.The combustor has a fluid disposed between the first liner and the firstconvector. The combustor has means for causing the fluid to move in adirection nonparallel to the central axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of a gas turbine engine;

FIG. 2 is an enlarged cross-sectional view of a combustor of the gasturbine engine of FIG. 1;

FIG. 3 is a perspective view of one embodiment of the combustor of FIG.2; and

FIG. 4 is a perspective view of an alternative embodiment of thecombustor of FIG. 2.

DETAILED DESCRIPTION

Referring to FIG. 1, an embodiment of a gas turbine engine 10 is shownhaving a compressor 12, a combustor 14, and a turbine 16. The combustor14 is in fluid communication with the compressor 12, and the turbine 16is in fluid communication with the combustor 14. The turbine 16 isconnected to the compressor 12 via a force-transmitting device 17, suchas a shaft or gear system. The combustor 14 defines a combustion zone 18of the gas turbine engine 10. In the embodiment of FIG. 1, the combustor14 of the gas turbine engine 10 is an annular combustor and has acentral axis 20. However, in other embodiments, the combustor 14 may betubular with a single can, tubular with multiple cans, tuboannular, orany other configuration known in the art. In the embodiment of FIG. 1,the combustor 14 is generally in the shape of a cylinder joined to aconical frustum. However, the combustor 14 may approximate any othershape or combination of shapes, such as a cylinder, an ellipticcylinder, a barrel, a funnel or a conical frustum.

Referring to FIG. 2, a portion of the combustor 14 is shown. Thecombustor 14 has a combustion zone 18 and a first liner 22 bounding thecombustion zone 18. As used herein, the term “bounding” shall mean“providing a limit to.” The first liner 22 has a first end portion 24and a second end portion 26 spaced a defined distance 28 from the firstend portion 24. In the embodiment of FIG. 1, the first liner 22 has acentral axis 29 that is generally the same as the central axis 20 of thecombustor 14. However, in other embodiments, such as a tubular combustorwith multiple cans, the central axis 29 of the first liner 22 may not begenerally the same as the central axis 20 of the combustor 14.

Referring to FIG. 2, the combustor 14 also has a first convector 30spaced apart from the first liner 22. The first convector 30 has a firstend portion 32 and a second end portion 34 spaced a defined distance 36from the first end portion 32. The first liner 22 is disposed betweenthe combustion zone 18 and the first convector 30. A defined volume 38is disposed between the first liner 22 and the first convector 30. Thedefined volume 38 has a first end portion 40 and a second end portion 42spaced apart from the first end portion 40. In the embodiment of FIG. 1,the first convector 30 has a central axis 44 that is generally the sameas the central axis 20 of the combustor 14 and the central axis 29 ofthe first liner 22. However, in other embodiments, such as a tubularcombustor with multiple cans, the central axis 44 of the first convector30 may not be generally the same as the central axis 20 of the combustor14. Also, in other embodiments the central axis 44 of the firstconvector 30 may not be generally the same as the central axis 29 of thefirst liner 22.

In the embodiment of FIG. 2, the first end portion 24 of the first liner22 does not contact the first end portion 32 of the first convector 30,such that the first end portion 40 of the defined volume 38 is open. Afluid may pass into the defined volume 38 between the first end portion24 of the first liner 22 and the first end portion 32 of the firstconvector 30. In FIG. 2, the second end portion 42 of the defined volume38 is closed. In other embodiments either or both of the first endportion 40 and the second end portion 42 of the defined volume 38 may beopen or closed.

Referring to FIG. 3, the combustor 14 has at least one means 45 forcausing a fluid positioned between the first liner 22 and the firstconvector 30 to move in a direction nonparallel to at least one of thecentral axis 29 of the first liner 22 and the central axis 44 of thefirst convector 30. In the embodiment of FIG. 3, the at least one means45 is a plurality of passages 46 positioned between the first liner 22and the first convector 30. In the embodiment of FIG. 3, the pluralityof passages 46 are formed by a first surface 48 of the first liner 22, afirst surface 50 of the first convector 30, and at least one wall 52connected to the first liner 22 and the first convector 30. However, inother embodiments the at least one wall 52 may be connected to only oneof the first liner 22 and the first convector 30. In the embodiment ofFIG. 3, the at least one wall 52 is a continuous wall, but in otherembodiments the at least one wall 52 may be formed by a plurality ofwall portions. The plurality of wall portions may be spaced apart. Oneordinary skill in the art will recognize that other structures mayperform substantially the same function as the at least one wall 52 andthat any of such structures may be substituted for the at least one wall52.

Referring to FIG. 2, each of the plurality of passages 46 has a firstend portion 54 proximate one or both of the first end portion 24 of thefirst liner 22 and the first end portion 32 of the first convector 30.Each of the plurality of passages 46 has a second end portion 56proximate one or both of the second end portion 26 of the first liner 22and the second end portion 34 of the first convector 30. Referring toFIG. 3, each of the plurality of passages 46 has a length defined as thelength of a line 58 that is positioned halfway between the at least onewall 52 defining the passage 46 and that extends from the first endportion 54 of the passage 46 to the second end portion 56 of the passage46. The length of at least one of the plurality of passages 46 isgreater than either one or both of the defined distance 28 of the firstliner 22 and the defined distance 36 of the first convector 30.

In the embodiment of FIG. 2 and FIG. 3, the plurality of passages 46 arespiral passages, i.e. the at least one wall 52 of the passages 46rotates about at least one of the central axis 20 of the combustor 14,the central axis 29 of the first liner 22, and the central axis 44 ofthe first convector 30. In the embodiment of FIG. 4, the passages 46 areserpentine passages. Other passage configurations are possible so longas the length of at least one of the plurality of passages 46 is longerthan either the defined distance 28 of the first liner 22 or the defineddistance 36 of the first convector 30. In FIG. 3, the combustor 14 hasthree passages 46. However, one of ordinary skill in the art willrecognize that the combustor 14 may have other numbers of passages 46.

Referring to FIG. 2, at least one of the plurality of passages 46 has afirst surface 60. In the embodiment of FIG. 2, the first surface 60 isformed by the first surface 48 of the first liner 22. At least one ofthe plurality of passages 46 may have at least one cooling device 62positioned therein. In the embodiment of FIG. 2, the at least onecooling device 62 is connected to the first surface 60 of the passage46. In the embodiment of FIG. 2, the at least one cooling device 62 is adimple 64, such as the dimple described in U.S. Pat. No. 6,098,397issued to Glezer et al. on 8 Aug. 2000. However, one of ordinary skillin the art will recognize that other cooling devices 62 may be used,such as trip strips, fins, or pins. Also, in other embodiments at leastone cooling device 62 may be connected to a second surface 66 of atleast one of the plurality of passages 46. Such second surface 66 may beformed by the first surface 50 of the first convector 30.

In the embodiment of FIGS. 1 and 2, the combustor 14 has a second liner68 bounding the combustion zone 18. The second liner 68 has a first endportion 70 and a second end portion 72 spaced a defined distance 74 fromthe first end portion 70 of the second liner 68. In the embodiment ofFIG. 1, the second liner 68 has a central axis 76 that is generally thesame as the central axis 20 of the combustor 14. However, in otherembodiments, such as a tubular combustor with multiple cans, the centralaxis 76 of the second liner 68 may not be generally the same as thecentral axis 20 of the combustor 14.

In the embodiments of FIGS. 1 and 2, the combustor 14 also has a secondconvector 78 spaced apart from the second liner 68. The second convector78 has a first end portion 80 and a second end portion 82 spaced adefined distance 84 from the first end portion 80. The second liner 68is disposed between the combustion zone 18 and the second convector 78.A second defined volume 86 is disposed between the second liner 68 andthe second convector 78. The second defined volume 86 has a first endportion 88 and a second end portion 90 spaced apart from the first endportion 88. In the embodiment of FIG. 1, the second convector 78 has acentral axis 92 that is generally the same as the central axis 20 of thecombustor 14 and the central axis 76 of the second liner 68. However, inother embodiments, such as a tubular combustor with multiple cans, thecentral axis 92 of the second convector 78 may not be generally the sameas the central axis 20 of the combustor 14. Also, in other embodimentsthe central axis 92 of the second convector 78 may not be generally thesame as the central axis 76 of the second liner 68.

In the embodiment of FIG. 2, the combustor 14 has a second plurality ofpassages 94 positioned between the second liner 68 and the secondconvector 78. In FIG. 2, the second plurality of passages 94 are formedby at least one wall 96. Other features of the second liner 68, secondconvector 78, second plurality of passages 94, and the at least one wall96 forming the second plurality of passages 94 are similar to thosefeatures set forth above of the first liner 22, first convector 30,plurality of passages 46 and at least one wall 52 forming the pluralityof passages 46.

Industrial Applicability

During operation of the gas turbine engine 10, a fluid, typically air,enters the compressor 12 of the engine 10. The compressor 12 compressesthe fluid and delivers the compressed fluid to the combustor 14. Aportion of the compressed fluid is delivered to the combustion zone 18of the combustor 14 where it is combusted with gas. This combustionprocess creates energy, a portion of which is used to drive the turbine16 of the gas turbine engine 10. Another portion of the energy createdby the combustion process manifests itself as heat. This portion ofenergy increases the temperature of the first liner 22 of the combustor14.

To cool the first liner 22, another portion of the compressed fluid fromthe compressor 12, hereinafter referred to as “the cooling portion ofthe compressed fluid,” is directed into the first end portion 54 of theplurality of passages 46 of the combustor 14. The motion of the coolingportion of the compressed fluid within the plurality of passages 46 willbe described by focusing on one of the plurality of passages 46. Thecooling portion of the compressed fluid enters the first end portion 54of the passage 46. The cooling portion of the compressed fluid contactsthe first surface 60 of the passage 46 and, thereby, withdraws heat fromthe first liner 22 of the combustor 14. In addition, the cooling portionof the compressed fluid contacts the at least one wall 52 of the passage46 causing the cooling portion of the compressed fluid to move in adirection nonparallel to at least one of the central axis 20 of thecombustor 14, the central axis 29 of the first liner 22, and the centralaxis 44 of the first convector 30. As used herein, “a directionnonparallel to” one of the central axes 20, 29, and 30 refers to thegeneral direction of the majority of the cooling portion of thecompressed fluid, not the particular movement of each individual fluidmolecule. In addition, “a direction nonparallel to” one of the centralaxes 20, 29, and 30 is not intended to describe movement in a directiontowards or away from one of the central axes 20, 29, and 30, e.g. themovement of the cooling portion of the compressed fluid typically causedby cooling devices 62, such as trip strips. Rotation of the coolingportion of the compressed fluid about at least one of the central axes20, 29, and 30 is an example of movement of the cooling portion of thecompressed fluid in a direction nonparallel to at least one of thecentral axes 20, 29, and 30. If the passage 46 is a spiral passage, thecooling portion of the compressed fluid is caused to move in a spiralpath. If the passage 46 is a serpentine passage, the cooling portion ofthe compressed fluid is caused to move in a serpentine path. During itsmovement through such a serpentine path, the cooling portion of thecompressed fluid may travel in a direction parallel to at least one ofthe central axes 20, 29, and 30, but at other points in the serpentinepath the cooling portion of the compressed fluid will be caused to movein a direction nonparallel to at least one of the central axes 20, 29,and 30.

Extending the length of the passage 46 ensures utilization of a greatercooling capacity of the cooling portion of the compressed fluid betweenthe first liner 22 and the first convector 30. In combustors 14 whereinthe cooling portion of the compressed fluid between the first liner 22and the first convector 30 simply travels either the defined distance 28of the first liner 22 or the defined distance 36 of the first convector30, the cooling portion of the compressed fluid may still have somecooling capacity remaining when the fluid exits the defined volume 38between the first liner 22 and the first convector 30. If the passage 46has one or more cooling devices 62 connected to the first surface 60,the cooling effect of the cooling portion of the compressed fluid isincreased. The cooling portion of the compressed fluid contacts thecooling device 62, and the cooling device 62 introduces turbulence intothe flow of the cooling portion of the compressed fluid. Therefore, awarmer segment of the cooling portion of the compressed fluid that isnear the first liner 22 is moved away from the first liner 22 and acooler segment of the cooling portion of the compressed fluid that isnear the first convector 30 moves towards the first liner 22, where itcan increase the cooling of the first liner 22.

In the embodiments described herein, compressed fluid enters theplurality of passages 46 via open first end portions 54 of the passages46. However, other means of entrance into the plurality of passages 46may be utilized, such as impingement jets or other orifices. In analternative embodiment not shown, in which the gas turbine engine 10 hasa serial cooling system, the cooling portion of the compressed fluid mayenter the plurality of passages 46 proximate the second end portion 56of the passages 46 and exit proximate the first end portion 54 of thepassages 46.

The operation of the second liner 68, second convector 78, secondplurality of passages 94, and at least one wall 96 forming the secondplurality of passages 94, in embodiments having such structures, issimilar to the operation discussed above of the first liner 22, firstconvector 30, plurality of passages 46, and at least one wall 52 formingthe plurality of passages 46.

Other aspects, objects, and advantages of this invention can be obtainedfrom a study of the drawings, the disclosure, and the appended claims.

1. A combustor, comprising: a combustion zone; a first liner boundingsaid combustion zone, said first liner having a first end portion and asecond end portion spaced a defined distance from said first endportion; a first convector spaced apart from said first liner, saidfirst convector having a first end portion and a second end portionspaced a defined distance from said first end portion, said first linerbeing disposed between said combustion zone and said first convector;and a plurality of passages positioned between said first liner and saidfirst convector, at least one of said passages having a length that isgreater than at least one of said defined distance of said first linerand said defined distance of said first convector.
 2. The combustor ofclaim 1 wherein said plurality of passages are spiral passages.
 3. Thecombustor of claim 1 wherein said plurality of passages are serpentinepassages.
 4. The combustor of claim 1 wherein said plurality of passagesare three passages.
 5. The combustor of claim 1 wherein at least one ofsaid plurality of passages includes at least one cooling devicepositioned therein.
 6. The combustor of claim 5 wherein said at leastone cooling device is a dimple.
 7. The combustor of claim 5 wherein saidat least one cooling device is at least one of a trip strip, a fin, anda pin.
 8. The combustor of claim 1 including: a second liner boundingsaid combustion zone, said second liner having a first end portion and asecond end portion spaced a defined distance from said first end portionof said second liner; a second convector spaced apart from said secondliner, said second convector having a first end portion and a second endportion spaced a defined distance from said first end portion of saidsecond convector, said second liner being disposed between saidcombustion zone and said second convector; and a second plurality ofpassages positioned between said second liner and said second convector,at least one of said second plurality of passages having a length thatis greater than at least one of said defined distance of said secondliner and said defined distance of said second convector.
 9. A gasturbine engine, comprising: a compressor; a combustor in fluidcommunication with said compressor, said combustor including: acombustion zone, a first liner bounding said combustion zone, said firstliner having a first end portion and a second end portion spaced adefined distance from said first end portion, a first convector spacedapart from said first liner, said first convector having a first endportion and a second end portion spaced a defined distance from saidfirst end portion, said first liner being disposed between saidcombustion zone and said first convector, and a plurality of passagespositioned between said first liner and said first convector, at leastone of said passages having a length that is greater than at least oneof said defined distance of said first liner and said defined distanceof said first convector; and a turbine in fluid communication with saidcombustor.
 10. The turbine engine of claim 9 wherein said plurality ofpassages are spiral passages.
 11. The turbine engine of claim 9 whereinsaid plurality of passages are serpentine passages.
 12. The turbineengine of claim 9 wherein said plurality of passages are three passages.13. The turbine engine of claim 9 wherein at least one of said pluralityof passages includes at least one cooling device positioned therein. 14.The turbine engine of claim 13 wherein said at least one cooling deviceis a dimple.
 15. The turbine engine of claim 13 wherein said at leastone cooling device is at least one of a trip strip, a fin, and a pin.16. The turbine engine of claim 9 wherein said engine includes a serialcooling system.
 17. The turbine engine of claim 9 wherein said combustorincludes: a second liner bounding said combustion zone, said secondliner having a first end portion and a second end portion spaced adefined distance from said first end portion of said second liner; asecond convector spaced apart from said second liner, said secondconvector having a first end portion and a second end portion spaced adefined distance from said first end portion of said second convector,said second liner being disposed between said combustion zone and saidsecond convector; and a second plurality of passages positioned betweensaid second liner and said second convector, at least one of said secondplurality of passages having a length that is greater than at least oneof said defined distance of said second liner and said defined distanceof said second convector.
 18. A method of cooling a liner of a combustorof a gas turbine engine, comprising: directing a fluid between a firstend portion of a first liner of a combustor and a first end portion of afirst convector of a combustor, at least one of said first liner andsaid first convector having a central axis; and causing said fluid tomove in a direction nonparallel to said central axis.
 19. The method ofclaim 18 wherein said causing said fluid to move in a directionnonparallel to said central axis includes causing said fluid to rotateabout said central axis.
 20. The method of claim 18 wherein said causingsaid fluid to move in a direction nonparallel to said central axisincludes causing said fluid to move in a spiral path.
 21. The method ofclaim 18 wherein said causing said fluid to move in a directionnonparallel to said central axis includes causing said fluid to move ina serpentine path.
 22. The method of claim 18 wherein said causing saidfluid to move in a direction nonparallel to said central axis iseffectuated by a plurality of passages located between said first linerand said first convector.
 23. A combustor, comprising: a combustionzone; a first liner bounding said combustion zone; a first convectorspaced apart from said first liner, said first liner being disposedbetween said combustion zone and said first convector, at least one ofsaid first liner and said first convector having a central axis; a fluiddisposed between said first liner and said first convector; and meansfor causing said fluid to move in a direction nonparallel to saidcentral axis.